If your using particle js for wordpress website and following this link :
http://cakewp.com/divi-tutorials/add-nice-moving-particles-background-effect/
Then, you may notice that the moving particle are above your content, in that case just give the content (it could be a column/row, or Button, or input field) a “z-index: 5(or more)”
In this picture, the search bar wasn't working. So, I gave
"z-index: 5"
to it. Now it works fine. Also, the particles are responding well.